你的句子是正确的
只要主要子句的动词不是过去式,也不是过去完成式,那麼附属子句的动词可以是任何可以正确表达意思的时态.然而,如果主要子句的动词是过去式或过去完成式,那麼附属子句的动词就必须是过去式或过去完成式.这个规则的例外是,附属子句是在表达众所周知的普遍事实和真理：
In the 1950s,English teachers still believed that a background in Latin is essential for an understanding of English.
Columbus somehow knew that the world is round.
Slaveowners widely understood that literacy among oppressed people is a dangerous thing.http://www.cybertranslator.idv.tw/grammar/sequence.htm看下这个网站